Signaling system for railroads



Aug. '18, 1942. w. H. HQPPE Y 2,293,139

SIGNALING SYSTEM FOR RAILROADS Filed Jan. 51, 1939 3 Sheets-Sheet 1 (H: I G) 4 INVENTOR' W. H. HoPpe, Deceased ATTORN'EY I Au 18, 1942. w. HOPPE j 2,293,139,

' sxemmue SYSTEM FOR RAILROAUS I Filed Jan. 31,1939 7 5 Sheets-Sheet 2 Fig.1.B.

Q INVENTOR 0 W H. Ho 2 Deceased 6 7 BY A. M. Hoggzgdmmistmtrix ATTORNY w. H.'HOPPE SIGNALING SYSTEM FOR RAILROADS Y Filed Jan. :51, 1939 s Sheets-Sheet :5

ppe, Dececpsed ATTORNEY NVENTOR xlnlgo Patented Aug. 18, 1942 2,293,i39 SIGNALING SYSTEM FOR RAILROADS Walter H. Hoppc, deceased, late of Rochester,

N. Y., by Alice Maijgren Hoppe, administratrix, Rochester, N. Y., assignor to General Railway Signal Company, Rochester, N. Y.

Application January 31, 1939, Serial No. 253,837 16 Claims. (01. 246-33) The present invention relates to track circuits for absolute-permissive block signaling systems and the system itself, and more particularly to such a system in which undivided blocks are employed between successive signals. This feature also permits the ready addition of continuous inductive train control.

An absolute-permissive .block signaling system is a system for single track train operation and signaling which aifords the usual double block protection behind a train moving through a single track section and which absolutely prevents the entrance of a train in an opposite direction through a single track\section when such section has once been occupied by a train. It is the usual practice in absolute-permissive block signaling systemsto have a track relay at each end of a block so that there is a track relay at the entrance to the block for each direction of traffic. If the usual divided block is employed the source of track circuit current is located at an intermediate point in the block.

In accordance with the present invention it is proposed to employ an undivided block and to' apply pulsating current to opposite ends of the block alternately at a very rapid rate and to connect track relays to opposite ends of the block alternately at the same very rapid rate' in such a manner that each track relay is energized from a source of current applied at the opposite end of the block, but can never be energized by the source of current applied to the same end of the block. This structure not only permits a track relay to be employed at each end of the block, but it also affords track circuit current at the exit end of the block for either direction of train travel, which current may be inductively picked up by suitable car-carried receiving apparatus on the car.

More specifically it is proposed to provide an alternating current transmission line continuously supplied with alternating current of commercial frequency, which in the present instance is assumed to be 60 cycles. It is also proposed to provide a synchronous vibrator at the junction between successive blocks, which vibrator alternately connects a track relay and a source of alternating current to the track circuit at that end, for bothv of the two adjacent blocks. These vibrators are so tuned and connected that alternating current is applied to the track circuit at one end, while a track relay is connected to the other end and so that another source of alternating current is connected to the otherend of this track circuit, whilethe'track relay is connected to the track circuit at said one end, these vibrators inthe specific arrangement shown com-, mutating the alternating current in a manner so that pulsating current of plus polarity is applied to one end of attack circuit, whereas pulsating current of negative polarity is applied to the other end of the track circuit. It is further proposed in accordance with the present invention to intermittently apply these pulsating currents to the track circuits at various rates to characterize coded impulses, and to apply these coded impulses in accordance with trafiic conditions in advance; toprovide suitable de-coding apparatus at the entrance end of each block, for each direction of traflic and to control wayside signals through the medium of this de-coding apparatus. It is also' proposed to provide suitable car-carried apparatus inductively coupled with the track circuit ahead of the train together with suitable amplifying and de-coding apparatus on the train for visually indicating on the train conditions of traffic in advance of the train as reflected by the coded currentin the track circuit ahead.

Other objects, purposes, and characteristic features of the present invention will in part be pointed out hereinafter and is in part obvious from the accompanying drawings.

In the drawings Figs. 1A, 1B and 1C when laid side by side in that order shows a portion of a single track section including two complete blocks and theadjacent ends of two other blocks of railway track equipped with the invention; Fig. 1A also illustrating the car-carried appararatus which is employed when cab signal indications are desired.

Track-way structure Referring to Figs. 1A, 1B and 10, when laid side by side, these drawings illustrate blocks X and Y and the adjacent ends of blocks W and Z. These blocks are divided by insulating joints l2 to form track circuitable track sections.v The entrance end of each block is provided with a ignal S. The signals for eastbound trafiic have been designated S S 5 and S and the signals for west-bound traiiic haave been designated S S", S and S Since the apparatus at the entrance to each block for each direction of trafiic is the same it will sufiice to describe the apparatus illustrated for the signal S in Fig. 1A of the drawings. Referring to the apparatus associated with signal each junction between successive blocks is provided with a vibrator such -as vibrator V These vibrators include an electro-magnet l3 and a permanent magnet N-S and two tuned armatures or reeds M. The reference number M in each case contains an exponent corresponding to the signal with which the reed is associated.

At the west end entrance of the block X is provided a code following track relay T connected to the track circuit of block X through the medium of the right-hand contact I4 of the vibrator V At the same end of this block X is provided a transformer Tr which is controlled in accordance with traffic to the rear of signal S and in advance of the signal S and this transformer Tr through the medium of'this same contact I4 of the vibrator V supplies pulsating current of negative polarity to the west end of the block X during the intervals between the connections of relay T to the track circuit. This code following relay T has its polar contact biased to a left-hand position and responds to move this contact from that position only inresponse to current of positive polarity, as is also true of relays T and T The code following track relays T T and T, on the other hand, are biased to their right-hand position, and are operated from this right-hand position only in response to pulsating current of negative polarity. These track relays T T T T T" and T are sufficiently slow dropping so as not to move their contacts between successive oscillations of said vibrating reeds I4, but are sufficiently quick acting to drop betweenimpulses of the 180 impulse per minute coding rate. The contact I5 of the track relay T when in its right-hand actuated position completes an energizing circuit fora slow acting track repeater relay A whereas this contact I5 when in its normal left-hand position and with the relay A energized completes an energizing circuit for the slow acting track repeater relay B. It is thus seen that the relay B can be energized only if the vibrating contact I5 is repeatedly moved from one extreme to the other extreme position at either the "[5 or the 180 impulse per minute coding rate.

The trackway apparatus for signal S also includes a transformer Tm, which may be energized with magnetizing current flowing intermittently in opposite directions in accordance with intermittent operation of the track relay T One circuit for this transformer Tra may be traced from the terminal of a suitable battery, through the contact I6? of the track relay T assuming the left-hand position, through onehalf of the primary winding of the transformer T111 through a front contact I! of the relay B to the terminal Another circuit for energizing the primary winding of the transformer Tra and for producing magnetic flux in the opposite direction may be traced from the terminal (-1-) of the same battery, through the contact I6 assuming its right-hand position, through the other half of the primary winding of the transformer, through front contact I! of the relay B to the terminal It is thus seen that intermittent operation of the code following track relay T causes the flux in the transformer Tm to be alternately reversed, thereby inducting alternating current voltage in the two secondary windings associated with this transformer Tra One of these secondary windings is connected to a full-wave rectifier which is in turn connected to a code following relay l80R through a condenser l9 whereas the other one of the secondary windings is connected to the code following relay 1511 through a second full-wave rectifier.

The relay T59R1 is energized when the track relay T operates at either the 75 impulse per minute coding rate or the 180 impulse per minute code rate, whereas the relay IBUR, by reason of the provision of condenser I9 will pick up only if the track relay T operates at the 180 impulse per minute coding rate.

It will be noted that signal S is energized and lighted only if the relay I8BR is energized, that the caution yellow lamp Y will be energized only if the relay 15R is energized and the relay IBUR is deenergized, whereas the stop or red lamp R is energized only when both of these relays are deenergized. There is also provided a slow dropping track repeater relay TR which is energized only so long as the track relay T operates at either the 75 impulse per minute coding rate or the 180 impulse per minute coding rate. This is true because if the relay T were held in its right-hand position permanently the relay B would be deenergized so that the transformer Tra would also be deenergized. As a result of the deenergization of the transformer Tm, and also if the relay T is not intermittently energized, or is permanently deenergized, neither the relay I53 or the relay 1803 would be energized, thereby opening both of the energizing circuits for the track repeater relay TR. Each signal location is also provided with the usual directional stick relay, which for signal S has been designated SR Each signal location is also provided with a coding unit, which for the signal 8* comprises a coding motor M and coding contacts I56 and NBC. The motor M drives the contacts and i300 for closing the former 75 andlatter times per minute.

Car-carried apparatus Each train equipped with cab signalling or brake control apparatus is provided with receivers R, one locatedover each track rail just ahead of the first wheels and axles of the train. These receivers comprise cores of laminated iron provided with coils preferably so connected in series that their voltages are cumulative and are preferably included in a tuned circuit leading to an amplifier A. The out-put circuit of this amplifier is connected to the winding of a car-carried code following relay CR; This code following relay CR'through contacts l5 and Hi controls cab signals through circuits and apparatus the same as just described in connection with signal S along the track, and for this reason the carcarried apparatus has been designated by like reference character having an exponent c.

Operation As heretofore pointed out each of the code following track relays T T and T are biased, as by a spring 20 to the negative position; whereas each" of the code following t'rack'relays T T and T" are biased to the positive position as by a spring 2|. Similarly, under clear traffic conditions the east end of each block has applied thereto pulsating current of positive polarity, the alternating current being rectified by the vibrating contacts I4 M M etc., the pulsating current being coded at the 180 impulse per minute code rate, whereas the west end of each block is supplied with pulsating current of negative polarity rectified by the vibrating contacts [4 [4", M etc., this pulsating current being also coded at the rate of 180 impulses per minute. In order to conventionally illustrate, in the drawings,

the clear lamp G of the relays SR/assume their energized position. Under the particular trafiic conditions shown in the drawings all of the track relays for west-bound traffic, namely, the track relays T T and T have been illustrated by solid line in their biased right-hand position, which, indicates that these track relays are not receiving coded current,

Whereas the track relay T is shown by solid line in its left-hand biased position to manifest that this relay is not receiving coded current, this by reason of the occupancy of the block Z, and the track relays T and T which are receiving coded current of 75 and 180 impulses per minute, re-

spectively, have their contacts shown dotted in both of their extreme positions to indicate that these track relays T and T are receiving coded current from their track circuits. Each current pulse flowing to these relays T and T is commutated by its respective vibrating contact I 4 and I4". By positive polarity is meant a polarity of current on the track circuit which will move the contacts, of track relays T, T and T for instance, from their biased position and which will cause the track relays T T and T to be operated to their biased position, whereas by current of negative polarity is meant a polarity of current which will operate the track relays T T and T from their biased position and will urge the track relays T T or T to their biased position.

Referring to the complete system as illustrated in the drawings, let us assume that there is an east-bound train, which has been illustrated as not being equipped with cab signaling apparatus, in block Z and that there is an equipped train in block W. Under the conditions assumed all of the signals illustrated for governing west-bound trains will, of course, assume the stop condition in which the red lamp is energized, whereas the signal S immediately in the rear of the unequipped train will have its red lamp energized and assume its stop position, the signal S second in the rear of the unequipped train will be assuming its caution condition by the energization of its yellow lamp, and the signal S third in the rear of the unequipped train and directly ahead of the equipped train will be assuming its proceed or clear condition, that is, will have its green lamp energized.

With the block Z occupied, as illustrated, the code following track relay T will assume its lefthand biased position, resulting in the deenergization of the relays A and B and deenergization of the relays 15R and ISOR, as a result of which the red lamp R or signal S is energized through a circuit including the back contact of relay IBIJR, and the back contact 26 of the relay 15R in series. Also, with the relays 15R and IBHR deenergized their respective contacts 2'! and 28 will be open, thus deenergizing the slow dropping repeater track relay TR The directional stick relay SR is, however, in its picked up condition with its stick circuit closed. This stick relay SR was picked up as the unequipped train t passed from the block Y'int'o the block Z. (When this train t still occupied the block .Y the back contact 29' was closed by reason of the occupancy of the block Y and the contacts 30 and 3| of the relays 15R and llllIR closed before the contact 32 of the track repeater relay TR opened, as a result of which a pick-up circuit was closed for the directional stick relay SR This stick relay SR was then primarily stuck up through a stick circuit including its front contact 33 and back contacts 34 and 35 of the relay IBIOR, and 15R, respectively. This directional stick relay SR was then secondarily stuck up through another stick circuit including its front contact 33 and back contact 36 of the track repeater relay TR This stick relay SR will, of course, be dropped as soon as the block Z becomes unoccupied, this by reason of the fact that the pick-up 'circuit will be opened at the back contacts 30 and 3| of the coding relays 15R and IBIIR before it is closed at the front contact 32 of the track repeater relay TR With the track repeater relay 'IR deenergized and the directional stick relay SR energized and with the opposing directional stick relay- SR deenergized a circuit is completed for applying current to the primary winding of the transformer Tr which may be traced as follows: beginning at one wire of the transmission line 60, back contact 40 of the relay TR coding contact 15C of the coding motor M front contact of the directional stick relay SR", back contact 42 of the directional stick relay SR through the primary winding of the transformer Tr to the other wire of the transmission line. The energization of the primary winding of the transformer Tr allows the contact I4 of the vibrator V"* to apply pulsating current to the east end of the block Y intermittently at the 75 impulse per minute coding rate.

The flow of this pulsatin current of positive polarity in the track circuit of the block Y causes the code following relay T at the entrance end of this block to be intermittently operated from its biased position at the coding rate of 75 operations per minute. This will cause the contact l5 of the track relay T to intermittently apply current to the relay A thereby causing it to assume its energized position and to close its contact 64 With this contact 64 closed the intermittent operation of the contact l5 of the track relay T will cause the relay B to assume its energized position, thereby closing its front contact 65 to connect the mid-point of the transformer Tra to the terminal of a suitable source of direct current. Operation of the contact N5 of the track relay T to its opposite positions at the rate of '75 complete cycles per minute will cause the direct current applied to the primary winding of the transformer Tra to be reversed at a rate to pick up the code responsive relays 15R through the medium of its full-wave rectifier, but this energization of the transformer Trafi will not cause energization of the code responsive relay IR because the condenser l9 substantially blocks the flow of alternating current of 75 cycles per minute. With the relay 15R energized and the relay l8llR deenergized a circuit is closed for i the caution lamp Y of the signal S through the back contact 25 of relay l8llR and the front contact 26 of the relay 15R. The picking up of the relay 15R due to the train t leaving the track circuit Y opens the back contacts 30 and 35 in the pick-up and stick circuits of the direc-. tional stick relay SR and shortly after picking up causes the track repeater relay TR. to pick up and open its back contact 36 in the then' closed stick circuit of the relay SR so that this directional stick relay SR becomes deenergized. With the stick relay SR deenergized andv the track repeater relay 'TR energized the transformer T1 is energized by alternating current coded at the 180 impulse per minute rate through the following circuit": beginning at one wire of the transmission line 6!], front contact 46 of the relay TR, contact ISEiC controlled by the coding motor M ,'back contact il of the directional stick relay SR back contact 62 of the opposing directional' stick relay SR through the primary winding of the transformer Tr, to the other wire of the transmission line Bil;

With the transformer Tr energized by alternating current pulsatcd at the 180 impulse per minute rate the secondary winding of this transformer through the medium of the vibratin contact Hi applies pulsating current of positive polarity to theeast' end of the. block X. This puleating current of positive polarity impulsedi at the 180 impulse per minute code rate will cause the track relay TRfi'to be alternately operated to its extreme positions 180" times per minute. This will cause the relays A and B to be energized for reasons heretofore pointed out and will cause the transformer Tm to be energized alternately by direct current of opposite polarity so as to induce in its secondary windings alternating current'voltage of 180 cycles per minute frequency. This voltage induced in the secondary windings of the transformer T111 will cause both of the relays R and I3GR to be energized. With the relay I8JR energized the green lamp G of the signals is energized through a circuit including the front contact of the relay [8012 Since the track repeater relay TR isnow energized and the directional stick relay SR? is deenergized, the same as was the case of similar relays associated with the signal S the block W next in'the rear will be energized at the exit end thereof for eastbound'traffic by pulsating current of positive polarity imp'ulsed at the 189 impulses per minute code rate through the medium of transformer T1 and vibrating contact Hi Since the code following relay CR carried by the railway vehicle is energized by alternating current inductively received from the pulsating current in the track rails, this relay CR will operate in the same manner as did the track relay of the block before such train entered the block containing" such track relay. In other words, the code following relay CR, on the car will be actuated in the same manner as the track relay of the block would be actuated if the train had not entered such block and for this reason the cab signal lamps G, Y or R will give the same indication throughout the entire block as was indicated at the entrance of such block, providing traffic conditions in advance did not change in the meantime. Obviously, this carcarried code following relay CR will be energized by alternating current irrespective of whether the pulsating track circuit current is of positive or negative polarity. Although all of the west bound signals S 5 and S assume the stop condition under the assumed traffic conditions it should be understood that these signals clear up in the'rear of the last east-bound train moving through the stretch.

The applicant has thus provided a system of absolute-permissive block signaling in which pulsating current of opposite polarity is applied to o'pp'o'site ends of the same block in intermeshed relation so that positive impulses are only present when negative impulses are absent, and negative impulses are present only when positive impulses are absent, and in which this pulsating current is applied to the track circuit by the vibrating contacts which are not readily harmed as would be the case if electrolytic or copperoxide type rectifiers were employed. Also, the structure is such that if a particular vibrator should cease to function no current would be applied to that end of the track circuit and no current will be received at the other end of that track circuit, thereby resulting in a structure constructed on the side of safety and preventing the false clearing of a signal. Also, sincethe pulsating current is intermittently applied to the track to characterize a code more favorable shunting of a track circuit by a train may be accomplished by reason'of the fact that the current. received from the track circuit must at all times be sufficient to pick up a relay and not merely suflicient to hold up a relay, thereby resulting in quick and safe effective shunting of the track relay. Furthermore, if a particular vibrator should become detuned, or for some other reason not operate in synchronism with the alternating current supply, only deenergization of a track relay could result because the vibrating contact cannot under any conditions connect the transformer and the track relay for a particular end of the track circuit to such track circuit at the same time. The system of the present invention avoids the necessity of dividing each block into two track circuits and furthermore, affords an alternating current supply to the exit end of. a track. circuit under favorable traffic conditions for either direction of train movement and at the same time permits trains to follow each other through a single track section with the usual caution and danger block protection between trains following each other and. also absolutely blocks the movement of trains in opposite directions through a single track section.

Having thus shown and described one rather specific embodiment of the present invention it isdesired to be understood that the particular system illustrated has been selected to illustrate the underlying principles of the present invention and one manner in which these principles may be applied to absolute-permissive block signaling, and it is to be understood that the invention may be applied to a system in which staggered signals are employed instead of opposite signals at the same point on the track for governing traffic in opposite directions, as illustrated. Although only one form of the present invention has been illustrated the applicant does not limit the invention to the particular system illustrated except as demanded by the scope of the following claims.

What is claimed as new is:

1. Trackway apparatus for absolute-permissive-block wayside or cab signaling systems for railroads; the combination with a single track stretch divided into track sections by insulating joints; a pulsating source of current connected across the exit end of each section for one direction of traflic; a pulsating source of current of the same frequency so timed that the pulses occur between the pulses of the first mentioned pulsating source applied across the exit end of each section for the opposite direction of traffic; a track relay connected across the rails at each end of each section; contact means included in series with each track relay for. commutating only the pulsating current from the source applied to the opposite end of such section flowing in the 'track circuit including such source, such track relay and such contact means in series; coding means for coding said pulsating current to produce either a clear or a caution code; and apparatus controlled by said track relays efiective upon movement of a train into said stretch to cause shunting of the rails of the firstsection of said stretch and to cause the removal of the pulsating current from the entrance end for that direction of movement, from all of the remaining sections of said stretch and efiective upon movement of such train through said stretch to cause pulsating current to be applied at the exit end, for that direction of travel, of each section in the rear of said train andto cause coding of the current applied to the exit end for that direction of travel, of the section first in the rear of the section occupied by such train to characterize a caution code and to cause the application of a clear code to all of the remaining sections to the rear of the occupied section. ,7

2. Trackway apparatus for absolute-permissive-block wayside or cab signaling systems for railroads; the combination with a'single track stretch divided into track sections by insulating joints; a, pulsating source of current connected across the exit end of each section for one direction of trafiic; a pulsating source of current but of the opposite polarity of the same frequency and so timed that the pulses occur between the pulses of the first mentioned pulsating source and applied across the exitend of each section for the opposite direction of trafilc; a polarized code following track relay connected across the rails at each end of each section; contact means included in series with each track relay for connecting such track relay across the track rails only when the pulsating current applied to the opposite end of said section flows, whereby each section, for a particular direction of traffic, including a contact of the mechanism at said junction for applying pulsating current by, applying one polarity wave of each of a plurality of cycles from said alternating current source to such exit end; means at the exit end of each section, for the opposite direction of traffic, including a contact of the mechanism at such junction for applying pulsating current by applying the other polarity wave of each of a plurality of cycles from said alternating current source to such exit end; a polarized track relay connected across the rails at each end of each track section, commutating means for each track relay including a, contact of the mechanism at that junction for closing the circuit for such track relay only when .impulses of the pulsating current applied to the other end of the same section by the next mechanism in advance are present; coding mean for codingthe pulsating current as it isapplied to theexit end of aisection; and apparatus controlled by said track relays effective upon move- -'ment of a train into said stretch to cause shunting of the rails of the first section of said stretch and to cause the removal'of the pulsating current from the entrance end, for that direction of movement, from all of theremaining sections of said stretch.

4. In combination, a section of. railway track insulated from adjacent track by insulating joints, a source of alternating current available at both the entrance and the exit end of said section, an electro-magnetically operated contact means at each endof said section operated by and. in synchronismwith the, cycles of said alternating current, a track relayat' the entrance contact means, the track relay included in series therewith, the track rails of such section and the pulsating current source applied across the other end comprise a track circuit; coding meansfor coding said pulsating current to produce either a clear or a caution code for each track circuit; and apparatus controlled by said track relays effective upon movement of a train into said stretch to cause shunting of the rails of the first section of said stretch and to cause the removal of the pulsating current from the entrance end for that direction of train movement, from all of the remaining sections of said stretch and effective upon movement of such train through said stretch to cause pulsating current to be applied at the exit end, for that direction of travel, of each section in the rear of said train and to cause the application of a caution code to the exit end for that direction of travel, of the section first in the rear of the section occupied by such train and to cause the application of a clear code to all of the remaining sections of said stretch in the rear of such train.

3. Trackway apparatus for absolute-permissive-block wayside or cab signaling systems for railroads; the combination with a single track stretch divided into track sections by insulating joints; a common source of alternating current available at each junction between adjacent sections; mechanism including a double throw electro-magnetically operated contact operated from said alternating current source to close alternate contacts during alternate waves of a cycle of alend of said section, the contact means at the exit end being connected in series with said source and across the track rails to intermittently apply current from said source to said track rails and the contact means at the entrance end of said section intermittently connecting said track relay to said track rails in synchronism with the intermittent application of. current to said track rails at said exit end, whereby said track rails may form parts of other circuits during the intervals between said connections, and a signal controlled by said track relay.

5. In combination, a section oi railway track dividedfrom adjacent track by insulating joints; a source of alternating current availableat both ends of said section, two track relays, an electromagnetic vibratory contact at each end of said section said contacts being vibrated by alternating current from said source and connecting the ends of said, track circuit to two circuit branches during each cycle of said alternating current, the branch first connected in a cycle forone end applying a source of current to that .end and for the other end connecting one of.sai d track relays across the track rails at such other end of said section and thesecond connected branch for said other endconnectinga source of current to such other end of said section and the second connected branch at said one end connecting the otherof said track relays to such one end across the track rails, whereby the, track rails of said section form parts of two different track circuits one having a track relay at one end of said section and the other having a track relay at the other end of said section which track circuits exist alternately and once for each cycle of said alternating current.

6. In a signaling system for governing the ternating current; means at the exit end of each movement oi trains through a single track ec tion, thecombination with a single track stretch divided into sections by insulating joints, a twoelement multiple contact commutating means at each junction of adjacent sections, a transmission line extending along said stretch of track, a source of alternating current for operating all of said commutating means in synchronism through the medium of said transmission line, a first set of track circuits each including a track relay included in series with one of the multiple contacts of one element of the communicating means at the entrance end of each section and onecontact of the other element of the communicating means at the exit end of the same section for one direction of trafiic included in series with a secondary winding of a transformer energized from said source of alternating current through the medium of said transmission line, a second set of track circuits each including a track relay included in series with the other of the multiple contacts of the other element of the communicating means at the entrance end of each section and the other contact of said one element of the communicating means at the exit end of the same section for the other direction of traific included in series with a secondary winding of a transformer energized from said source of alternating current, and signals for governing traffic in both directions through said stretch governed by the track relays of said first and said second i set of track circuits.

7. In a signaling system for governing trafnc in both directions through a stretch of single track; the combination with a stretch of single track divided by insulating joints into sections; a transmission line extending along said stretch of single track; a tuned reed electro-magnetically actuated vibrator having two double throw elements and tuned to a particular frequency; two track circuits for each section, one including 'a track relay, one element of a first vibrator engaging its first contact, the track rails 'of such section, the other element of a second vibrator engaging its first contact and 'a source of alterhating current of said frequency transmitted '1 over said transmission line, and the other track circuit including a track relay the other element .of the second vibrator engaging its second contact, the track rails of such section, the one element of said first element engaging its second contact and said source of alternating current transmitted over said transmission line, and signals 'for governing trafiic in both directions governed by said track relays of said stretch of single track.

8. In a signaling system, a stretch of track divided into sections by insulating joints; a source "of alternating current; a double throw electromagnetically operated contact at each end of each of said sections; two track circuits for each section each including the track rails ofsuch section, one track circuit including a track relay at one end, said source of alternating current at the other and said double throw contacts at both ends closed during the first period of a cycle of said alternating current and the other track circuit including a track relay at the other "end, said source of alternating current at said one end and said double throw contacts at both ends closed during the second period of a cycle of said alternating current, and signals for governing trafiic in both directions governed by said track relays.

9. In a signalingsystem for "governing the inovementof trains through a single track section, the combination with a single track stretch divided into sections by insulating joints,- a twoelement multiple contact commutating means at each junction of adjacent sections, a transmission line extending along said stretch of track, a source of alternating current for operating all of said commutating means in synchronism through the medium of saidtransmission line, a first set of track circuits eachincluding atrack relay included in series withone of the multiple contacts of one element of the communicating means at the entrance end of each section and one contact of the other element of thecommunicating means at the exit end of the same section for one direction of trafiic included in series with a secondary winding of a transformer energized from said source of alternating current through the medium of said transmission line, a second set of track circuits each including a track relay included in series with the other of the multiple contacts of the other element of the communicating means at the entrance end of each section and the other contact of said one element of the communicating means at the exit end of thesame section for the other directionof traffic included in series with a secondary winding of a transformer energized from said source of alternating current, means at the alternatingcurrent source end of each track circuit for coding the current in such track circuits in accordance with traffic conditions in the adjacent section and in the section beyond the adjacent section, decoding means associated with each traclr relay, and a signal for each decoding means controlled by such decoding means. p

10. In a signaling system for governing trafiic in both directions through a stretch of single track; the combination with a stretch of single track divided by insulating joints into sections; a transmission line extending along said stretch of single track; a tunedreed electro-magnetically actuated vibrator havingtwo double throw elements and tuned to a particular frequency; two track circuits for each section, one including a track relay, one element of a first vibrator engaging its first contact, the track rails of such section, the other elementof a second vibrator engaging its first contact and a source of alternating current of said frequency transmitted over said transmission line, and the other track circuit including a track relay the other element of the second vibrator engaging its second contact, the track rails of such section, the one element of said first element engaging its second contact and said source of alternating current transmittedover said transmission line, means at the alternating current source end of each track circuit for coding the current in such track circuits in accordance with traffic conditions in the adjacent section and in the section beyond the adjacent section, decoding means associated with each track relay, anda signal for each decoding means controlled by such decoding means.

11. In a signaling system, a stretch of track divided into sections by insulating joints; a source of alternating current; a double throw electro-magnetically operated contact at each end of each of said sections; twotrack circuits for each section eachincluding the track rails of such section and one track' circuit including a track relay at one en'd,said source ofjalternating current at the other and. said double :throw contacts atboth'ends closed during the first period 'of a cy'cle'of said alternating'current and the'other track circuit including a-track relay at the other end, said source of alternating current at said one endand said double throw contacts at both ends closed during the second period of a cycle of said alternating current, means at the alternating current source end of each track circuit for coding the current in such track circuits in accordance with traffic conditions in the adjacent section and in the section beyond the adjacent section, decoding means associated with each track relay, and a signal for each decoding means controlled by such decoding means.

12. In a signaling system for governing the movement of trains through a single track section, the combination with a single trackv stretch divided into sections by insulating joints, a twoelement multiple contact commutating means at each junction of adjacent sections, a transmission line extending along said stretch of track, a source of alternating current for operating all of said commutating means in synchronism through the medium of said transmission line, a first set of track circuits each including a track relay included in series with one of the multiple contacts of one element of the communicating means at the entrance end of each section and one contact of the other element of the communicating means at the exit end of the same section for one direction of traffic included in series with a secondary winding of a transformer energized from said source of alternating current through the medium of said transmission line, a second set of track circuits each including a track relay included in series with the other of the multiple contacts of the other element of the communicating means at the entrance end of each section and the other contact of said one element of the communicating means at the exit end of the same section for the other direction of traffic included in series with a secondary winding of a transformer energized from said source of alternating current, and apparatus controlled by said track relays and effective upon movement of a train into said stretch of track by the shunting of the rails of the first section of said stretch to cause the re moval of the current from the entrance end for that direction of movement from all of the remaining section of said stretch of track.

13. In a signaling system for governing the movement of trains through a single track section, the combination with a single track stretch divided into sections by insulating joints, a twoelement multiple contact commutating means at each junction of adjacent sections, a transmission line extending along said stretch of track, a source of alternating current for operating all of said commutating means in synchronism through the medium of said transmission line, a first set of track circuits each including a track relay included in series with one of the multiple contacts of one element of the communicating means at the entrance end of each section and one contact of the other element of the communicating means at the exit end of the same section for one direction of trafiic included in series with a secondary winding of a transformer energized from said source of alternating current through the medium of said transmission line, a second set of track circuits each including a track relay included in series with the other oi the multiple contacts of the other element of the communicating means at the entrance end of each section and the other contact of said one element of the communicating means at the exit end of the same section for the other direction of traiiic included in series with a secondary winding of a transformer energized from said source of alternating current, and apparatus controlled by said track relays and effective upon movement of a train into said stretch of track by the shunting of the rails of the first section of said stretch to cause the removal of the current from the entrance end for that direction of movement from all of the remaining section of said stretch of track, and for causing the signal at the entrance end of each section to indicate stop as the train enters it and to cause the signal at the entrance end of the section in the rear of such train to indicate caution.

14. In combination, a section of railway track divided from adjacent track by insulating joints; a source of alternating current available at both ends of said section, two track relays, an electromagnetic vibratoryicontact at each end of said section said contacts being vibrated by alternating current from'said source and connecting the ends of said track circuit to two circuit branches during each cycle of said alternating current, the branch first connected in a cycle for one end applying a source of current to that end and for the other end connecting one of said track relays across the track rails at such other end of said section and the second connected branch for said other end connecting a source of current to such other end of said section and the second connected branch at said one end connecting the other of said track relays to such one end across the track rails, whereby the track rails of said section form parts of two different track circuits one having a track relay at one end of said section and the other having a track relay at the other end of said section which track circuits exist alternately and once for each cycle of said alternating current, and signals for governing traffic in both directions governed by said track relays.

15. In combination, a section of railway track divided from adjacent track by insulating joints; a source of alternating current available at both ends of said section, tro-magnetic vibratory contact at each end of said section said contacts being vibrated by alternating current from said source and connecting the ends of said track circuit to two circuit branches during each cycle of said alternating current, the branch first connected in a cycle for one end applyinga source of current to that end and for the other end connecting one of said track relays across the track rails at such other end of said section and the second connected branch for said other end connecting a source of current to such other end of said section and the second connected branch at said one end connecting the other of said track relays to such one end across the track rails, whereby the track rails of said section form parts of two difierent track circuits one having a track relay at one end of said section and the other having a track relay at the other end of said section which track circuits exist alternately and once for each cycle of said alternating current, coding means for coding the alternating current in each track circuit at that end where the alternating current is applied, decoding means controlled by each track relay, and signals for governing traffic in both directions governed by said decoding means. i

16. In a coded track circuit system of railway signaling, the combination of a stretch of two two track relays, an elec- I direction running single track that is arranged in sections, means including movable contacts.

at a given end of each of said sections for there supplying the section rails with recurring pulses of first direction energy of a particular polarity rection energy supply,. a code following track relayof the polar type which is operated against its bias by currentnof one .polarity and tends to operate in the opposite ,directiontinr response to current of the opposite :polarityat .each end of each section, means including :movable contacts periodically operated for, connecting each code following track relay to. the section rails at the corresponding end of atracksection when energy is supplied to the opposite end of that section and. for disconnecting z-saidtrack relay from the section rails when energy is supplied at the same end of that track section, whereby each track relay is connected to the track rails only when energy is supplied to the opposite end of of the energy impulses by which that relay is.

operated, and trafiic governing apparatus controlled by said decoding means for controlling traffic in both directions through said stretch of track,

ALICE MAIJGREN HOPPE, Administratrix of the Estate of Walter H. Hoppe,

Deceased. 

